The invention relates to balanced building ventilation systems.
Ventilation is desirable for many homes and other buildings. This is particularly so in view of modern construction practices resulting in structures which are relatively xe2x80x9ctight.xe2x80x9d In other words, the interior is relatively sealed with reference to the outdoor ambient. Energy conservation, particularly in colder climates, is a major motivation.
Inadequate ventilation can cause moisture or odor problems within a building. Of perhaps greater concern, negative pressure inside a building can result in draft failure of combustion appliances such as water heaters and furnaces. Any combustion appliance requires a supply of combustion air. In some jurisdictions, building codes require that a building ventilation system be provided.
To address these concerns and, in some cases, building code requirements, a variety of air supply ventilators are commercially available. Some ventilators include motor-driven blowers. Other ventilators are simply passive openings. To avoid a cold draft and to reduce building heat loss as a result of ventilation, many air supply ventilators include an air-to-air heat exchanger, whereby outdoor ambient air entering the interior of the building is warmed by heat exchange with interior air exiting to the outdoor ambient. Fireplaces are often considered a desirable feature in a home. However, fireplaces present special problems. In particular, a fireplace is, in general, a de-pressurizing device, and can produce a negative building pressure. In some jurisdictions, when a home is built with a fireplace, building codes require that forced draft inducers be employed on combustion appliances such as gas water heaters and furnaces.
In one aspect, a system is provided for ventilating the interior of a building surrounded by an outdoor ambient. The system comprises a fireplace including a firebox, an exhaust gas flue connected to the firebox for exhausting gas from the firebox to the outdoor ambient, a motor-driven draft inducer connected to the exhaust gas flue for forcing exhaust gas flow out to the outdoor ambient, a channel for conveying outdoor ambient air into the building interior, and a motor-driven blower within the channel for forcing ventilation airflow into the building interior to replace building interior air lost to exhaust gas flow.
In another aspect, a fireplace heat recovery ventilator device is provided for use in combination with a fireplace within the interior of a building surrounded by an outdoor ambient, the fireplace including an exhaust gas flue connection for exhausting gas to the outdoor ambient. The device comprises a flue section connectable in series with the fireplace exhaust gas flue connection between the fireplace and the outdoor ambient; a motor-driven draft inducer connected to the flue section for forcing exhaust gas flow out to the outdoor ambient; a heat exchange structure attached to the flue section; a housing defining a chamber enclosing the heat exchange structure, the housing including an inlet connection connectable to one end of a fresh air inlet duct having another end connected to the outdoor ambient, and an outlet connection connectable to one end of a ventilation air delivery duct having another end connected to the building interior, the inlet and outlet connections being arranged such that air entering the inlet connection passes through the chamber past the heat exchange structure and exits via the outlet connection; and a motor-driven blower connected for forcing the ventilation airflow through the chamber and out through the ventilation air delivery duct into the building interior to replace building interior air lost to exhaust gas flow.
In yet another aspect, a method is provided for ventilating the interior of a building surrounded by an outdoor ambient. The method comprises providing a fireplace which includes an exhaust gas flue open to the outdoor ambient, providing a channel for conveying outdoor ambient air into the building interior, forcing exhaust gas flow out through the exhaust gas flue, and forcing ventilation airflow through the channel into the building interior to balance the exhaust gas flow.
Embodiments of the invention thus provide a ventilation system for a building, which ventilation system employs the fireplace as an element of the ventilation system, and which potentially satisfies code requirements for a ventilation system, in cases where there are such code requirements.
Embodiments of the invention have the effect of making the fireplace a pressure-neutral device, rather than being a de-pressurizing device. Potentially, in those jurisdictions where building codes require the provision of draft inducers on appliances such as gas water heaters and furnaces when a home has a fireplace, the code may be amended to not require such draft inducers when a fireplace is installed in combination with embodiments of the invention.